Typewriting machine



Hannan/bnn..242s.$15,121,552

NVE T0 JM ATTO R. G. THOMPSON TYPEWRITING MACHINE Filed Feb Jan. 3, 1939.

Patented Jan. 3, 1939 i UNITED STATES PATENT, OFFICE TYPEWRITING MACHINE Application February 18, 1936, Serial No. 64,461

10 Claims.

'I'his invention utilizes sound-deadening principles to quiet the blows of the type on the platen.

The platen may preferably have a jacket of hard rubber, and is mounted on a hollow, perforated tube by a series of resilient supporting units. Each unit consists of a metal disk of less diameter than the platen-shell, fitted tightly on the said tube, a metal sleeve tightly engaging the inner surface of the platen cylinder, the sleeve having an inwardly turned rim with a centrally located hole of diameter larger than the disksupporting tube, and an annular ring of soft rubber, surrounding the tube and secured, as by 'vulcanizatiom to the disk and the rim of the metal sleeve. The units are preferably intertting and thus the outer cylinder is supported by a practically continuous metal shell.

The hollow tube receives the platen-shaft and may be secured thereto by means of spacing collars and set-screws.

In a modification, the cylindrical facing may be forced over a thin metal tube. andresilient mounting units employed only at the endsthereof. The hollow, perforated tube, in the modified form, also serves to dampen vibrations within the platen and so reduce reverberations therein.

Ihe annular rings, which are the link between the platen-surface and the platen-shaft, act as v means for dampening vibrations Within the platen, interpose a refractive medium through which the sound waves must pass to the platen-shaft, and additionally are an efficient means of insulating against the transmission of shocks from the platen-surface to the shaft. The' rings are suiciently resistant to make the platen support the heavy blows necessary to make clear, manifolded copies. They are, however, subjected to a shearing stress whenever the platen is struck at any point around its circumference. The distortion resulting from such shearing stress makes the rubber less communicative of vibrations, and consequently increases its value as a shock and sound insulating medium. Thus the elciency of the mountings increases as the force of the blow increases. This is an advantage over the usual form of resilient mounting, which, being under compression, is compacted, and thereby rendered less efcient, by the blow.

50 5 It is well known that sound waves may be reflected and refracted from a rectilinear course whenever they undergo an unequal acceleration or retardation. The reilection of a portion of a sound wave back upon itself is eective to cause 55, interference in the following waves, and obvious- (Cl. 19V-147) ly lessens the volume of 'sound which penetrates the sound-reilecting medium. The refraction of the sound waves, in passing from one medium to another in which the waves travel with less or greater velocity, will so diffuse the wave that the 5' sound penetrating the refracting media is, in practical effect, lessened. The greater the difference in the velocity of the sound wave in passing from one medium into another, the greater the refractive effect, and the less objectionable the I0' sound which penetrates the refractive wall.

Other features and advantages will hereinafter appear.

In the accompanying drawing,

Figure 1 is a sectional plan view of one form 15" of platen disclosed herein.

Figure 2 is a transverse cross-sectional View taken through the platen of Figure 1 at 2-2.

Figure 3 is a perspective view of a disassembled platen-supporting unit. 2l)` Figure 4 is a sectional view of a modification of the platen of Figure 1.

A platen 20, Figure 1, is journaled on a platenshaft 2|, in carriage end-plates 22, and is arranged to be revolved by a knob 23, or by a 25 ratchet 24, the latter in connection with the familiar carriage-return lever (not shown). Types 25 may print against the platen in the usual manner.

y The platen 2U is constructed with a cylindri- 30 cal shell 26, which may be of the usual hard platven-rubber, a tube 2l having a multiplicity of perforations 28 and a series of shock-absorbing and sound-insulating units 29, by means of which the platen-shell 26 is mounted on the tube 2l. 35" The units 29, as shown in Figure 1, may be intertting, and may include a cylindrical shell 30, having at one end a section 3| of reduced radius, the said reduction being equivalent to the thickl ness of the wall of the shell 30, and an inturned 40 rim 32, the width of which leaves an opening of diameter larger than that of the tube 2l. The outside diameter of the shells 30 permits a forced lit within the platen-shell 26. At each end of the platen 20, the units include a flange 33, Figures 1 and 3, of smaller diameter than the shells 30, and arranged to fit snugly on the tube 2l, to which they may be secured by set-screws 34. In the intermediate units, as shown in Figure l, a metal disk 35 replaces the flanges 33, the said 50V disks being equal in diameter to the flanges, and arranged to be frictionally fitted on the tube 21.

An annular ring 36, of rubber, or other resilient, shock-absorbing material, is interposed between, and concentrically secured to, the' rimsv32 552 of the shells 30, and to the flanges 33 or the disks 35 of the end or intermediate units respectively. The outside diameter of the annular ring 36 may be substantially equal to the flange 33. As shown in Figure I, the hole in the ring 36 is of unequal, but concentric, diameters, engaging the tube 21 for a portion of the width of the ring, and being of larger diameter than the tube over the balance.

The right and left end units 29 are complementary, but, as shown in Figure 1, the righthand unit, instead of having the extended shell 30, is constructed with a shallow cup 31 arranged to fit tightly within the shell 30 of the adjacent unit. At the left end of the platen, a short metal cylinder 38, of outside diameter equal to the shell 30, may be slipped over the end-portion 3| and brazed or soldered thereto, to complete the supporting surface for the platen-shell.

With the units in interfitted position, as shown in Figure 1, the said units being frictionally, rather than permanently, joined, the platen-shell 26 is forced over the assembled units, the platenshaft 2| passed through the tube 21, and the complete platen secured to the said shaft by means such as the collars 4|J and set-screws 4|.

It will thus be seen that the platen-shell 26 is in intimate contact, over its entire length, with a practically continuous supporting cylinder, which being of greater density than the platen-shell, acts'to reflect and refract the .passage of sound waves from the surface to the interior of the platen-structure. In addition, the platenshell and its supporting cylinder float in rubber, and are not in direct contact with the tube 21 or the platen-shaft 2| at any point.

A- blow from the type 25 will subject the annular ring 36 to a shearing stress, a's thefslight inward movement of the rim 32 will be opposed 4by the reaction of the anges 33 or the disks 35. The tensioning of the rubber, resulting from the distortion of the ring 36 under shear, not only effectively reduces the transmission of sound to the tube 21 and the platen-.shaft 2|, but additionally insulates against the Ytransmission of the shock of impact, preventing the generation of sounds at the end-plates 22.

The reverberation of the sounds which reach the interior of the platen-structure is muffled and broken up by 'the barriers established by the contact of the portion of the rings 36 with the tube 21, and by the perforations 28 in the tube.

The platen illustrated in Figure 4 is very light in weight, and may be used on portable machines. The outer shell 26 is forced over a tightly'tting metal cylinder 45, which extends the full length of theshell 26. The striking surface thus formed is mounted on the perforated tube 21, preferablyV at each end only. The resilient mounting units include an inverted metal cup 46, having a wall 41 which tightly engages the cylinder 45,'and a rim 48, which surrounds the tube 21 in spaced relationship therewith', as shown. The annular rubber ring 36 is Vof somewhat smaller overall diameter than that used in the resilient unit of Figure 3, and, as shown, is located within the wall 41 of the cup, and vulcanized to the rim 48. The ilange 33 is vulcanized to the outer surface of the ring 35, and is held onth-e tube 21 by the set- Screw 34. The tube 21 receives the platen-shaft 2|, and is secured thereto by the collars 4|) and set-screws 4|.

By inverting the metal cup 46, the platen-striking surface is adequately supported at the extreme ends', a desirable condition in portable typewriters, in which the platen is substantially shorter than in standard machines. Reverberations within the platen are dampened by the perforations 28 of the tube 21, and by the annular rings 36, which, as shown, engage the said tube over a portion of the width of the rings.

Variations may be resorted to within the scope of the invention, and portions of the improvements may be used without others.

Having thus described my invention, I claim:

1. A platen for a typewriting machine, comprising, an outer cylindrical shell against which types may strike, a perforated tube disposed axially within said shell, and a series of resilient rings interposed at spaced intervals between said shell and said tube, to afford a yieldable support for said shell on Vsaid tube, whereby to isolate vibrations in the shell, said rings dividingy the interior of said shell into a series of chambers intercommunicative via the perforations of said tube to dissipate sound occurring in any of said chambers. l

2. A platen for a typewriting machine, comprising, an outer cylindrical shell against which types may strike, a perforated tube disposed axially within said shell, and a series of resilient rings interposed at spaced intervals between said shell and said tube, to afford a yi-eldable support for said shell, whereby to isolate vibrations in the sh'ell, said rings dividing the interior of said shell into a series of chambers intercommunicative via said perforated tube to dissipate sound occurring in any of said chambers, each of said rings being of a diameter and bore 'to clear the shell and perforated tube respectively, each ring engaging the shell and tube at opposed ends of the ring only.

`3. A typewriter platen comprising a hollow cylinder against which types may strike, a series of connected shells within said cylinder, each of said shells including a radial flange, a disk adjacent each flange and arranged to receive a shaft for support of the platen, and a resilient member xed to each flange and al corresponding disk, whereby to dampen sound-vibrations within the cylinder and isolate same from the shaft.

4. Atypewriter platen comprising a series of interlocking shells in axial alignment, each shell having an inturned end portion forming a radial flange, a shaft supporting said platen on the typewriter and including a series of disks mounted thereon, one foreach of said flanges and adjacent thereto, and a resilient member joining each flange and a corresponding disk, whereby to afford a sound-dampening mount for the platen on the shaft.

5. A typewriter platen comprising a series of interlocking shells in axial alignment, each shell having an inturned end portion forming a radial flange, a shaft supporting said platen on the typewriter and including a series of disks mounted thereon, one for each of said flanges and adjacent thereto, and a resilient member joining each iiange and a corresponding disk, whereby to afford a sound-dampening mount for the platen on the shaft, the inturned portion of each shell being of stepped formation to telescope an adjoining shell so as to present a substantially even periphery for the platen. l Y A 6. A typewriter platen comprising a hollow cylinder against which types may strike, a plurality of inwardly-directed flanges on said cylinder, a shaft for mounting the platen onrthe typewriter and including a plurality of disks adjacent said flanges and in substantial parallelism therewith, andaI plurality of resilient members connecting each flange to a corresponding disk, whereby to dampen sound-,vibrations within said cylinder and isolate same from the shaft.

7. A typewriter platen having a cylindrical shell against which types strike, an axial member in said shell, and supports resilientlysecuring said shell to said member, said supports including a ring, of resilient material of the order of rubber, annularly separated, between its two opposite sides, from said shell and member, said ring being connected only at said opposite sides to said shell and member respectively so that one side is movable relatively to the opposite side, perpendcularly to the platen axis, whereby said ring is subjected to shearing stress by the blows of the types against the shell.

8. A typewriter platen having a tubular shell against which types may strike, an axial member within said shell, a series of tubes intertting at their ends so as to form a substantially continuous tube, said tubes being severally in contact with the bore of said shell, each tube having an inturned ange and the axial member having a plurality of iianges paired with but separated from the tube flanges, and sound isolating rings connecting the paired flanges.

9. A sound deadening platen, for a typewriting machine, having an outer facing against which types may strike, means for mounting the platen in the machine, and a vstructure interposed bei tween the facing and the mounting, said structure including paired members arranged side by side and through which sound waves travel at a certain velocity, the paired members being separated by contiguous material through which sound waves travel at a different velocity, one member being supported by said mounting and in turn supporting said contiguous material on one side of the latter, the contiguous material at said one side and said one member being separated from said facing, the other member supporting said facing and being supported by the opposite side of said contiguous material, the contiguous material at said opposite side and said facing-supporting member being separated from said mounting, said contiguous material forming the sole medium whereby the mounting-supported member extends support laterally to the facing-mounting member.

l0. In a typewriter platen having a facing against which types may strike and a shaft for mounting the platen in the typewriter, devices for insulating against the passage of soundvibrations to the platen-shaft, said devices including a member supporting the facing but separated from the shaft, a member supported by the shaft but separated from the facing, said members being disposed substantially at right angles to the platen-shaft, and a resilient body,

of the order of rubber, secured to and interposed between said members, so that the platen-facing supporting member is yieldably supported to tend to retract upon impact of the type and thereby subject said resilient body to shear stress and thus enhance its ability to isolate sound vibrations.

RUSSELL G. THOMPSON. 

